forward masking
11.49 forward masking. Condition in which the signal occurs after the masking sound.
backward masking
11.48 backward masking. Condition in which the signal occurs before the masking sound.
central masking
11.47 central masking. Masking that occurs when a signal is presented to one ear and a masking sound to the other ear. Annotation The site of central masking is thought to be in the higher auditory pathways of the brain.
speech interference level
11.46 speech interference level. One-fourth of the arithmetic sum of the band sound pressure levels for octave bands with nominal midband frequencies of 500, 1000, 2000, and 4000 Hz. Unit, decibel; abbreviation, SIL; symbol, LSi.
intelligibility
11.45 articulation; intelligibility. Percentage of speech units correctly received out of those transmitted. Annotation 1 The word “articulation” is used when the units of speech material are syllables or other meaningless fragments of speech; the word “intelligibility” is used when the units of speech material are complete, meaningful words, sentences, or phrases. The term “intelligibility” is commonly associated with speech production as well as with speech reception. Annotation 2 The type of speech material used should be specified (i.e., phonemes, syllables, words, phrases, or sentences). Speech identification is provided by an appropriate adjective, for example, syllable articulation, vowel (or consonant) articulation, word intelligibility, sentence intelligibility, etc.